{placeholder} stands in for a picture that is not there yet: a grey box with two crossing lines and its size - or a text - in the middle, written as inline SVG (tags/_lib/placeholder.php). Wireframes and layouts get their proportions right before the photos exist, without a placeholder image service.

The first parameter is the size, '600x300'. Or give the proportions with ratio='16:9': the box is then width pixels wide (640) and says its ratio. fluid makes the box as wide as its container, the height following from the proportions - the box for a responsive column. text replaces the size in the middle and is the accessible name.

The view box is the size itself, so the box scales without distortion and the text stays centred, shrunk to fit a narrow box. The colours are --pad-placeholder-surface, -line and -text on .pad-placeholder, with light-dark() defaults written once per page. A size or ratio that is not two whole numbers is an error under the strict check. {lorem} is the same idea for text.